International Publication WO/2007/100105 discloses a technique for producing a multi X-ray beam by distributing electron sources two-dimensionally and controlling the electron sources individually. The divergence angle of the multi X-ray beam is determined by the opening conditions of X-ray extraction windows disposed in a vacuum.
However, there are cases where it is desirable to adjust the divergence angle of the multi X-ray beam depending on the imaging conditions. To accommodate this, in International Publication WO/2007/100105, a vacuum X-ray shielding plate 23 is added as a first shielding plate, and combined with an atmospheric X-ray shielding plate 41 constituting a second shielding plate. The divergence angle of the multi X-ray beam can be freely selected in accordance with the irradiation conditions of the object, given that this second shielding plate provided in air can be easily replaced.
Japanese Patent Laid-Open No. 09-187447 discloses a movement mechanism for moving the distance between two X-ray tubes (foci) or the interfocus distance of one X-ray tube, based on information on an imaging magnification factor or imaging geometry for stereo imaging. Japanese Patent Laid-Open No. 09-187447 further discloses providing another movement mechanism that enables adjustment of an X-ray aperture, such that an appropriate X-ray exposure range can be set in response to driving of the above movement mechanism.
Japanese Patent Laid-Open No. 2006-136500 discloses a movement mechanism of a movable aperture device moving aperture blades to a prescribed position based on information on an imaging range and forming a diagnostic imaging region, in a fluoroscopic imaging apparatus. Herein, the state of the aperture blades in the case where a monitoring imaging region is formed, and the state of the aperture blades in the case where a diagnostic imaging region is formed are disclosed. The four aperture blades move at high speed when generating monitoring image data, as a result of an aperture movement control unit receiving arrival signals from a pixel value comparing unit, and form a diagnostic imaging region.
Japanese Patent Laid-Open No. 2001-120526 discloses an X-ray fluoroscopic apparatus provided with a cradle for the patient to lie down on, and a first X-ray tube and a semiconductor detector that are respectively attached to first and second ends of a C-arm whose arms are capable facing one another with the cradle therebetween. This apparatus is equipped with a second X-ray tube that is positioned further away than the distance from the semiconductor detector to the first X-ray tube. Further, this apparatus is also equipped with semiconductor detector movable supporting means for movably supporting the semiconductor detector so as to be capable of taking a first position or orientation facing the first X-ray tube and a second position or orientation facing the second X-ray tube.
Japanese Patent Laid-Open No. 2001-137221 discloses a CT gantry provided with two angiographic arms in addition to a CT imaging X-ray tube and an X-ray detector. One angiographic arm is a frontal arm provided with an X-ray tube and an X-ray image receiving device for performing vertical angiography of a sample. The other angiographic arm is a lateral arm provided with an X-ray tube and an X-ray image receiving device for performing horizontal angiography of a sample. According to Japanese Patent Laid-Open No. 2001-137221, the CT gantry is removed to a position that does not obstruct the angiography, and the frontal arm and the lateral arm are moved to an angiography position, based on an instruction from an operator. Also, the frontal arm and the lateral arm can be removed to a position that does not obstruct the CT imaging, based on an instruction from an operator.
In the operating room, the surgeon moves the C-arm device himself or herself to locate the best angle. The surgeon needs to perform fine positional setting of the entire C-arm device. The present invention is premised on applying an X-ray imaging apparatus having a plurality of X-ray sources (multi X-ray source, MBX), in order to facilitate this positional setting.
Specifically, the following three types of changes to the examination region are available, in the case where fluoroscopy is performed after narrowing the examination region with an X-ray aperture in order to reduce radiation exposure to the patient.
The first involves scaling the examination area, the second involves shifting the examination region, and the third involves changing the examination direction.
A plurality of aperture units need to be changed in conjunction with each of these three types of changes to the examination region. In the case of shifting the examination region, it is considered necessary to maintain the examination direction and also preferably the examination area, and in the case of changing the examination direction, it is considered necessary to maintain the examination center and also preferably the examination area.
However, as for conventional apparatuses that use a plurality of X-ray sources, there are only commonly known examples of a stereo imaging apparatus and a double C-arm device, as described above, and there is no known technology of a C-arm device that uses a multi X-ray source. Therefore, there is no recognition of the above problems, and consequently no technique for solving these problems.
On the other hand, there are cases where it is desirable to use a plurality of X-ray sources to examine a plurality of examination areas substantially at the same time (or sequentially). In these cases, it is envisioned that it may be desirable to change the selection of one X-ray source in response to a change in the selection of another X-ray source. However, there is currently no technique for meeting such a requirement.